A semiconductor circuit is made to show a high performance by high densification achieved by miniaturization of transistor, resistance, wiring and the like constituting a circuit, as well as high-speed responses. In addition, lamination of wirings has enabled higher densification and higher integration of semiconductor circuits. The semiconductor production techniques that have enabled the above include shallow trench isolation, metal plug and damascene process. The “shallow trench isolation” means transistor element isolation, the “metal plug” means three-dimensional wiring using a metal having a structure penetrating an interlayer dielectric film, and the “damascene process” means an embedding technique of copper wiring. The technique essential for each step such as shallow trench isolation and the like is chemical mechanical polishing. The chemical mechanical polishing (hereinafter sometimes to be abbreviated as “CMP”) is constantly used for each step of shallow trench isolation, damascene process, interlayer dielectric formation and metal plug embedding. These fine patterns are formed by transcription of a resist mask formed by a photolithography step. As miniaturization proceeds, the depth of the focus of the projector lens used for the lithography becomes shallow, and the required level of flatness of the worked surface of a substrate becomes high, since the concaves and convexes on the substrate needs to be smaller than the depth. By planarizing the worked surface by CMP, a flat surface of a nano order or atom level can be obtained, and high performance by three-dimensional wiring, i.e., lamination, becomes possible. CMP is currently introduced for planarization of an interlayer dielectric film, formation of BPSG film (silicon oxide film doped with boron, phosphorus and the like) or shallow trench isolation region, formation of plug and embedding metal wiring and the like.
For formation of a shallow trench isolation region, CMP is used for removing a redundant insulating film made from silicon oxide etc. formed on a substrate, and a stopper film is formed beneath the aforementioned insulating film to stop polishing. As a stopper film, silicon nitride and the like are generally used, and the polishing end point can be easily determined by increasing the polishing rate ratio of the aforementioned insulating film and the stopper film. It is desirable to obtain a flat polished film by polishing to eliminate the difference between the levels of the insulating film and stopper film. To obtain a flat polished film, it is further desirable that the polishing should stop on the stopper film even when polished excessively and polishing of the insulating film and stopper film should not proceed.
Conventionally, it is known that a water-soluble organic compound such as polyacrylic acid, a salt thereof and the like is added to a slurry for CMP in an attempt to improve stability of abrasive grain in the slurry for CMP, control polishing rate, improve flatness, reduce difference in level, and suppress increase of difference in level due to excess polishing (see patent document 1 and patent document 2).
In addition, a system using a carboxylic acid polymer such as polyacrylic acid, a salt thereof and the like, and polyvinylpyrrolidone, a cationic compound and an amphoteric ion compound in combination is also known (see patent document 3).
On the other hand, a slurry for CMP comprised of at least one kind of water-soluble polymer selected from the group consisting of a polyacrylic acid having a weight average molecular weight of not less than 1 million and not more than 10 million and a salt thereof, β-cyclodextrin and colloidal silica is known (see patent document 4).